A police report into last October's terrorist attack on the Canadian parliament building shows officers missed their chance to stop the gunman because of miscommunication and a lack of proper training.

The report by Ontario Provincial Police released Wednesday said "the approach to the security and protection of Parliament Hill is highly inadequate....a grim reminder that Canada is ill-prepared to prevent and respond to such attacks."

The gunman, Muslim convert Michael Zehaf-Bibeau, shot and killed a security guard at a Canadian war memorial in Ottawa before commandeering a car and speeding to the nearby parliament building.

A woman who witnessed the attack tried to run for cover in a police woman's car. The report says the officer's radio message to another police car that could have intercepted the gunman was garbled.

The report also says Zehaf-Bibeau was able to storm the building because guards at the front door were unarmed. Royal Canadian Mounted Police, who did have guns, were under orders never to enter parliament with weapons.

Zehaf-Bibeau fired a number of shots in the halls before officers killed him.

The report says if the gunman had been better organized, there could have been casualties.